Sanatana Dharma ("Eternal Religion"), a.k.a Hinduism, is without any contest the "world champion" of Scriptures, both in its breath (covering 18 fields of knowledge, it has far more scriptures than all the other world religions put together) and its depth.

As the great Indologist Max Muller said,
"If I were asked under what sky the human mind has most fully developed the choicest gifts, has most deeply pondered on the greatest problems of life, and has found solution of some of them which well deserve the attention even of those who have studied Plato and Kant-I should point to India. And if I were to ask myself from what literature we here in Europe, we who have been nurtured almost exclusively on the thought of Greeks and Romans, and of one Semitic race, the Jewish, may draw that corrective which is most wanted in order to make our inner life more perfect, more comprehensive, more universal, in fact more truly human, a life not for this life only, but a transfigured and eternal life-again I should point to India."

The sheer number of scriptures should not be so surprising, in light of the fact that Indians have always considered all arts, sciences, and occupations as sacred, i.e. offering the opportunity to perfect one's love for God by carrying out our activities guided by the scriptures and the sages. Hence there are scriptures for meditation, administration, love-making, dancing, grammar, architecture, temple worship, and so on and so forth.

The Fourteen Fields of Knowledge
Indian scriptures span fourteen fields of knowledge (vidya) and four complements to the Vedas (upavedas). The fourteen fields are the four Vedas (Rik, Yajur, Sama, Atharva), the six vedangas (meter, etymology, phonetics, grammar, astrology-astronomy, rituals), and the four upangas (logic, enquiry, sacred history, code of social conduct). The four complements to the Vedas are medicine, politics-economics, warfare, and fine arts.
(The Mahabharata, Ramayana, as well as Sankhya, Patañjala, Pashupata and Vaishnava, form part of Dharma Shastras.)

The Six Categories
Another method is to classify all scriptures in six categories:

Shruti means "heard", i.e. divinely revealed scriptures. The shrutis are also known as prabhu-samhitas ("Commanding Treatises"). They refer to the four Vedas only.

All religions trace their scriptures to the revelation given by God to a single chosen messenger... except in Hinduism. The Vedas were not revealed to a single prophet. They existed in a subtle form before creation began, and were gradually revealed to a number of sages or rishis (over 800 of them, according to some calculations) in the depth of their meditation. Each Vedic mantra is dedicated to a particular deity (devata), and set in one of 19 possible meters (chhandas).
The word veda itself come from the Sanskrit root vid, "to know."
The four Vedas number all together over 20,500 mantras.

1. Rig Veda

It was revealed to Paila Rishi and dedicated to Agni, the fire god. It is presided by the planet Guru (Jupiter).
It is divided in ten books (mandalas), made of 1028 hymns (suktas), which comprise 10,552 mantras in total.
The Rig Veda originally had twenty-one recensions (shakhas), only five of which are still extant. It contains hymns on gods, soul, social life.
It contains the Aitareya and Kaushitaki Upanishads.

2. Yajur Veda

It was revealed to Vaishampayana Rishi and dedicated to Vayu, the wind god. It is presided by the planet Shukra (Venus).
It is divided in 40 parts (skandas), which comprise 1975 mantras in total.
It is divided in: 1) the Krishna ("Black") Yajur Veda book (the oldest), and 2) the Shukla ("White") Yajur Veda book (a later revelation to Sage Yajñavalkya, nephew of Sage Vaishampayana)
The Yajur Veda originally had 102 recensions (85 for the Black, 17 for the White) only four of the Black and two of the White are still extant today. It is a manual on rituals and sacrifices.
The Black contains the Taittiriya and Katha Upanishads, while the White contains the Isha and Brihadaranyaka Upanishads.

3. Sama Veda

It was revealed to Jaimini Rishi and dedicated to Aditya, the sun god. It is presided by the planet Mangal (Mars).
It is divided in:
1) Purvarcika, made of four parts (skandas), containing 585 mantras.
2) Uttararcika, made of 21 parts (skandas), containing 964 mantras.
Of the total of 1549 mantras, all but 75 of them come from the Rig Veda.
The Sama Veda originally had 1000 recensions, only three of which are still extant today. It contains devotional hymns, music, prayers for peace.
It contains the Chhandogya and Kena Upanishads.

Note: in the matter of Vedic sacrifices, the prayoga (operative) mantras are taken from the Rig Veda, adhwaryu (priestly) from the Yajurveda and the audgatra (singing) from the Samaveda.

4. Atharva Veda

It was revealed to Sumanthu Rishi and dedicated to Aditya, the sun god. It is presided by the planet Budha (Mercury).
It comprises:
1) Purvadha ("first half"), made of various discourses.
2) Uttarardha ("second half"), comprising the critical appreciation of rituals, etc.
The Atharva Veda is divided in four books (prapathakas), totaling twenty chapters (skandas) and includes 6,077 mantras.
It originally had 9 recensions, of which only two are still extant today.
It contains hymns to deities, creation stories, mantras to ward off evil and enemies, magic and tantra.
An astounding total of 93 Upanishads are found in the Atharva Veda, among which the famous Prashna, Mundaka, and Mandukya Upanishads.

Division of the Vedas
Each Veda comprises four parts:
a) The mantra-samhitas: hymns of praise to deities to attain material prosperity in this world and happiness in the next.
b) The brahmanas: manual for the performance of sacrificial rites.
c) The aranyakas: philosophical interpretations of the rituals.
d) The Upanishads, a.k.a. vedanta ("end of the Vedas"): the essence or mystical portion of the Vedas.
These four divisions of the Vedas are often described in terms of a divine harvest, where the samhita represents the tree, the brahmana the flower, the aranyaka the unripe fruit, and the upanishad the ripe, sweet fruit.

Smriti means "remembered". These are the secondary scriptures, of human composition.

A. The Four Upavedas ("Subsidiary Vedas")

1) Ayurveda ("Science of life and health"), associated with the Rig Veda:
Charaka Samhita by Charaka.
Susruta Samhita, by Susruta, on the science of rejuvenation.
Vagbhata Samhita by Vagbhata.
Kama Sutras by Vatsyayana, on the science of healthy sex.

3) Gandharva Veda ("Science of music and art"), associated with the Sama Veda:
Gandharva Shastra by Sage Bharata on the science of vocal and instrumental music and dance as a means to concentrate the mind on God.

4) Arthashastra ("Science of politics and economics").
Note: Other (minor) sources consider this fourth upaveda to be sthapatya shastra ("Science of mechanics and construction"), associated with the Atharva Veda.

Arthasastra dealing with the acquisition of material things like wealth by righteous means. Under this head, nitisastra, shilpasastra, the sixty-four kalas and also other physical and metaphysical subjects are included.

The kalas
According to the Vamakeshvara Tantra, there are 64 books called kalas. There are various lists of these 64 "arts". One such list is as follows:

Kautilya Artha Shastra by Sage Kautilya (a.k.a. Chanakya) (302 B.C.E.): a treatise on government by the prime minister of India's first great emperor, Chandragupta Maurya.
Chanakya Neeti by Chanakya (302 B.C.E.)

Note: the Mahabharata can also be classified as part of the artha shastra.

B. The Six Vedangas ("Organs of the Vedas")

According to tradition, these are to be mastered before the study of the Vedas.

The Vedangas (limbs of the Vedas) are six: siksha, kalpa, vyakarana, nirukta, chhandas and jyotisha. By using the name Vedanga the human origin of these subjects is indicated, although they are in close association with the Vedas.

Other classic texts on jyotisha:
Shani Mahatmya ("Greatness of Saturn").

6. Kalpa ("Methods of Rituals"):

i. Srauta kalpa, methods for the performance of sacrifices.

ii. Sulba kalpa, methods of measurements for the sacrifice area.

iii. Dharma kalpa, methods for ethics.
Out of eighteen texts of dharma shastra, the three most important are:
Manu Smriti ("The Laws of Manu") (150 B.C.E.), meant for the satya yuga.
Yajñavalkya Smriti ("The Laws of Yajñavalkya"), meant for the treta yuga.
Parashara Smriti ("The Laws of Parashara"), meant for the kali yuga.

The Itihasas are also known as suhrit-samhitas ("Friendly Treatises").
There are four epics:

1. Ramayana, by Sage Valmiki (500 B.C.E.). The epic of the avatar Rama and his consort Sita faced with the demon Ravana.

2. Mahabharata, by Sage Vyasa (1316 B.C.E.). The epic of the avatar Krishna, including the complete story of the Pandavas and Kauravas. Its importance is such that it is referred as the "Fifth Veda." According to its author, "It unveils the secrets of the Vedas, contains the essence of the Upanishads. It elaborates on the Itihasas and Puranas, astrology, morality and ethics, life science, medicine, charity and generosity, it is also a description of holy places of pilgrimage, rivers, forests, oceans and mountains. It is the greatest epic of mankind, rich with knowledge and applied knowledge. It is a book on theology, political philosophy; a scripture of devotion and action and is the synopsis of the Aryan scriptures". The Bhagavad Gita is a small part of this epic.

Often described as the "magnifying glass of the Vedas", tradition ascribes them to Sage Vyasa. By definition, the Puranas must deal with the following five topics (pancha-lakshana): 1) History; 2) Cosmology; 3) Secondary creation; 4) Genealogy of kings; and 5) World-cycles. There are eighteen main Puranas and eighteen subsidiary ones (upa puranas).

C. The Tamil Puranas

These are all Puranas glorifying Lord Shiva, as he incarnated Himself in the form of Dakshinamurti to teach the four Kumaras (sons of Brahma).
These Tamil Puranas are:
1. Siva Purana
2. Periya Purana
3. Siva Parakramam
4. Tiruvilayadal Purana

The Agamas do not derive their authority from the Vedas, but are not antagonistic to them.
They follow a four-fold method of worship: 1) jñana ("knowledge"); 2) yoga ("concentration"); 3) kriya ("esoteric ritual"); 4) charya ("exoteric worship").

The most important books on the Agamas are:
Ishvara-Samhita
Ahirbudhnya-Samhita
Sanatkumara-Samhita
Narada-Pancharatra
Spanda-Pradipika

The Agamas are divided into three categories: 1) The Vaishnava Agamas or Pancharatra Agamas (worship of Vishnu); 2) The Shaiva Agamas (worship of Shiva); 3) The Shakta Agamas or Tantras (worship of the Divine Mother or Shakti).

There are 28 Shaiva Agamas, of which the chief is the Kamika Agama.
There are two principal divisions in Shaivism, both based on these 28 Agamas as well as the Vedas: 1) Kashmir Shaivism, a.k.a. the pratyabhijna system, a non-dualistic philosophy; and 2) Southern Shaivism, a.k.a. shaiva siddhanta, a dualistic philosophy.
Each Agama has upa-agamas ("Subsidiary Agamas"). Of these, only fragmentary texts of twenty are extant.

C. The Shakta Agamas

There are 27 Shakti Agamas, usually in the form of dialogues between Lord Shiva and his consort Parvati.
The most important ones are:

The six darshanas or ways of seeing things, are usually called the six systems or six different schools of thought. The six schools of philosophy are the six instruments of true teaching or the six demonstrations of Truth. Each school has developed, systematized and correlated the various parts of the Veda in its own way. Each system has its sutrakara, i.e., the one great Rishi who systematized the doctrines of the school and put them in short aphorisms or Sutras
The Sutras are terse and laconic. The rishis have condensed their thoughts in the aphorisms. It is very difficult to understand them without the help of commentaries by great sages or rishis. Hence, there arose many commentators or bhashyakaras. There are glosses, notes and, later, commentaries on the original commentaries.

The darshanas are grouped into three pairs of aphoristic compositions which explain the philosophy of the Vedas in a rationalistic method of approach. These pairs are:nyaya and vaiseshikasankhya and yogamimamsa and vedanta

The shad-darshana (the six schools of philosophy) or the shat-shastras are:

1. Nyaya

Nyaya represents the logical approach to spirituality, founded by Gautama Rishi:
Nyaya Sutras by Gautama Rishi (350 B.C.E.): 537 sutras divided in five chapters, dealing with the analytical process of cognition.

2. Vaiseshika

Vaiseshika deals with the material aspect of creation and the path of discrimination, founded by Kanada Rishi:
Vaiseshika Shastra by Kanada Rishi: 373 sutras divided in twelve chapters, written as a supplemental science to nyaya, and acknowledging the authority of scripture.

3. Sankhya

Sankhya presents a dualistic conception of purusha (soul) and prakriti (nature), founded by Kapila Muni): Sankhya Shastra by Kapila Muni: six chapters describing the world as real, and the purpose of life is freedom by understanding the difference between purusha and prakriti.

Additional texts on sankhya: Sankhya Karika by Ishvara Krishna

4. Purva (or karma) mimamsa

Purva mimamsa deals with outer practices, i.e. rituals, and was founded by Sage Jaimini:
Mimamsa Sutras by Jaimini (200 B.C.E.) in twelve chapters.

5. Yoga

Yoga concerns itself with inner practice, and was founded by Patañjali Maharshi:
Yoga Sutras by Patañjali Maharshi (150 B.C.E.): 194 sutras divided in four parts, expounding on the eightfold limbs process of God-realization. It is also known as raja yoga.

Additional texts on yoga:
Hatha Yoga Pradipika. The first systematic exposition on the much misunderstood science of Hatha Yoga.
Gheranda Samhita. The classic tantric text on yoga in the form of a dialogue between the sage Gheranda and an inquirer.
Shiva Samhita. A detailed Sanskrit classic on the practice of yoga.

6. Uttara (or sharirika) mimamsa, a.k.a. Vedanta

Vedanta concerns itself with the realization of the Truth, and was founded by Sage Vyasa:
Vedanta Sutras by Sage Bhadrayana (350 B.C.E.
Brahma-Sutras by Sage Vyasa (1450 B.C.E.): 555 aphorisms presenting the entire philosophy of the Vedas. A good knowledge of the Upanishads is required before studying this work.

Additional texts on Vedanta: the Upanishads.
The word upanishad is derived from upa, "near;" ni, ";" and shada, "to sit by the side [of the guru]". It also means, "that which brings one to God's side."

Composed from 1450 B.C.E. onward, there are 108 authoritative Upanishads, out of which the main ones are:

The Bhagavad Gita, although part of the Mahabharata (Book Bhishma Parva, sections 13-42), is considered as an Upanishad. In this respect, it is said that "Just as the Upanishads are the cream of the Vedas, the Bhagavad Gita is the cream of the Upanishads. The Upanishads are the cows, Lord Krishna is the cowherd, Arjuna is the calf, and the Bhagavad Gita is the milk. The wise drink the milk of the Gita."

6. Brahma Gita (from the Skanda Purana, chapter 4 of the book Suta Samhita, and chapters 1-12 of the book Yajñavaibhava Khanda). Another version with the same name is found in Yoga Vasishtha, in the section on Nirvana, stanzas 173-181.

7. Brahmana Gita: this forms a part of the Anu Gita described above.

8. Bodhya Gita (from the Mahabharata, Book Moksha Parva, as a part of the book Shanti Parva)

9. Devi Gita (from the Devi Bhagavata, Book 7, chapters 31-40)

10. Ganesha Gita (from the Ganesha Purana, Book Krida Khanda, chapters 138-148): it is quite close to the Bhagavad Gita in format and contents.

16. Manki Gita (from the Mahabharata, Book Moksha Parva, as a part of the book Shanti Parva)

17. Pandava Gita (from the Mahabharata)

18. Parashara Gita (from the Mahabharata, Book Moksha Parva, as a part of the book Shanti Parva)

19. Pingala Gita (from the Mahabharata, Book Moksha Parva, as a part of the book Shanti Parva)

20. Rama Gita. Two versions exist:
1) the most common is from the Adhyatma Ramayana (a part of the Brahmanda Purana), Section 5 of the book Uttara Kanda, in which Lord Rama imparts the knowledge of the Self to his most devoted and dear brother Lakshmana;
2) the second one, common in Tamil Nadu, is from the Guru Jñana Vasishtha-Tattva Sarayana. This text comprises three parts, dealing with 1) knowledge (jñana), 2) spiritual practice (upasana), and 3) actions (karma).

21. Ramana Gita: this is a contemporary treatise written in Sanskrit by the South Indian sage Ramana Maharshi.

22. Shiva Gita (from the Padma Purana, Book Patala Khanda)

23. Shiva Shampaka Gita (from the Mahabharata, Book Moksha Parva, as a part of the book Shanti Parva)

31. Yama Gita. Three versions exist:
1) in the Vishnu Purana, Book 3, chapters 1-7;
2) in the Agni Purana, Book 3, chapter 381; and
3) in the Narasimha Purana, chapter 8.

B. Miscellaneous

Shandilya Bhakti Sutras by Sage Shandilya (100 C.E.)

Narada Bhakti Sutras by Narada. The classic work on the path of devotion by the great sage Narada, eternal companion of Krishna.

Devi Mahatmyam, a.k.a. Chandi or Durga Saptasati, which comes from the Markandeya Upanishad. The poetic narration of triumph of the Divine Mother over the forces of evil.

Sri Chakra

Saundaraya Lahari by Adi Shankaracharya

Shakta Upanishad

Subhagodayam

Adhyatma Ramayana

Tripura Rahasya

Tirukural by Tiruvalluvar (150 B.C.E.)

Tevaram: hymns of the Shaiva saints of South India

Tiruvachakam: hymns of the Shaiva saints of South India

Divya-Prabandham: hymns of the Alvar saints of South India

Songs of Sant Kabir

Abhangas of Sant Tukaram

Ramayana of Sant Tulasidas

VIII. Secular Writings of a Spiritual Orientation

A. Wisdom Tales (subhashitas)

This category includes wise sayings, instructions, fables and stories, either in poetry or in prose. Some of the most famous are:
Three Centuries of Verses by Bhartrihari
Subhashita-Ratna-Bhandagara
Katha-Sarit-Sagara by Somadeva Bhatta
Brihat-Katha-Manjari by Kshemendra
Panchatantra. Probably composed about 200 B.C.E., the great scholar Vishnu Sharma wrote these tales as a way to instruct in morality the three sons of a great king who had proved utterly resistant to the pursuit of knowledge until then.
Hitopadesha

B. Poetry (kavyas)

These are highly refined compositions in verse, prose, or a combination of the two.

1. Famous works in verse
Raghuvamsa and Kumara-sambhava by Kalidasa, the greatest in his category.
Kiratarjuniya by Bharavi
Shisupalavadha by Magha
Naishadha by Sri Harsha

2. Famous works in prose
Kadambari and Harshacharita by Bhattabana, the great genius in classical Sanskrit.

I am immensely indebted to the profound scholarship of Swami Sivananda Saraswati, founder of the Divine Life Society, for the compilation of this section on Hinduism. As the great swami wrote, "The Shruti (Vedas) is the root; the Smritis (treatises), Itihasas (epics) and Puranas (history) are the trunk; the Agamas (manuals of worship) and Darshanas (philosophies) are the branches; and the Subhashitas (wisdom tales), Kavyas (poetry), Natakas (dramas) and Alankaras (rhethorics) are the flowers of the tree of India's culture", showing that all spiritual writings of India have their root in the immortal Vedas